The present invention relates to a shrinking apparatus, and more particularly to a shrinking apparatus for heating and melting molded articles of thermoplastic resin such as expanded polystyrene or other thermoplastic disused articles by far-infrared rays, causing the same to be so reduced in bulk as to be handled with ease.
Molded articles of thermoplastic resin such as expanded polystyrene have the advantages of lightweight, excellent adiabatic and cushioning properties, and the like. Accordingly, such molded articles have been widely used as a variety of packing materials and containers instead of corrugated cardboard materials and wooden boxes.
After use, the molded articles of thermoplastic resin are scrapped or collected for reuse. However, bulky molded articles of thermoplastic resin as they are, not only cause inconvenience in transit, handling and the like, but also require expensive handling costs.
It is therefore required to minimize such molded articles in volume. Thus, there has been proposed a shrinking apparatus in which, while articles or expanded polystyrene molded articles are conveyed by conveying means such as a belt conveyor, far-infrared heaters opposite to the conveying means in a furnace heat and shrink the articles, causing the same to be reduced in bulk (See, for example, Japanese Publication for Unexamined Patent Application No. 81440/1986 and No. 104708/1987).
When far infrared rays are irradiated onto the articles, the articles are shrunk during the conveyance thereof and the max. height (entire height) thereof varies. In the conventional shrinking apparatus abovementioned, the far-infrared heaters can be vertically slided in their entirety according to the entire height of the articles prior to the treatment. However, provision is made such that the distance between the conveying means and the far-infrared heaters is constant in the conveying direction. Accordingly, as the bulk of the articles becomes smaller, the distance between the articles and the far-infrared heaters becomes greater. This fails to efficiently irradiate the far infrared rays to the articles. Thus, the conventional shrinking apparatus fails to achieve an efficient bulk reduction, thereby to lower the treatment capacity.